In a conventional substrate processing system for performing film formation on a wafer serving as a substrate, a powdery solid source, e.g., powdery tungsten carbonyl (W(CO)6) is used, as known in the art. This substrate processing system includes a chamber (ampoule) for accommodating the solid source, a film forming processing unit for performing film formation on the wafer, and a gas introduction line for introducing the solid source to the film forming processing unit by connecting the film forming processing unit and the chamber.
In this substrate processing system, the solid source is carried by a carrier gas to the film forming processing unit via the introduction line. The carried solid source is converted to a gas by a vaporizer or the like, and the gas is converted to a plasma in the film forming processing unit. Further, the film formation is performed on the wafer by the plasma (see, e.g., Japanese Patent Laid-open Publication No. 2006-93240 (FIG. 1)).
However, if the stand-by (idling) state of the substrate processing system is kept for a long period of time, powder particulates of tungsten carbonyl may grow to particles larger than the powder particulates in the introduction line or the chamber. These particles are discharged from the chamber or the introduction line during the film forming process, and then are introduced into the film forming processing unit. If the introduced particles are attached to the wafer, this may cause defects in semiconductor devices manufactured from the corresponding wafer.